1. Field of the Invention
The present invention relates to an interlock switch that is used in various image forming apparatuses, such as a copy machine, a facsimile, a printer, and a multifunctional apparatus thereof, and an image forming apparatus using the same.
2. Description of the Related Art
A conventional interlock switch mechanism that is used in an image forming apparatus will be described. In the image forming apparatus, covers are provided on a paper discharge port and a back surface to remove jammed paper. In general, one switch is used for one cover. However, two covers may be detected by one switch to save a space and reduce a cost.
The case where two facing covers are detected by one switch will be described.
FIG. 1 is a lateral view illustrating a printer body 1. In the printer body 1, a pressing member 3 is provided in a back cover 2 and a pressing member 6 is disposed in a paper discharge cover 4, and one switch (not shown in the drawings) is turned on, in a state where the two covers 2 and 4 are closed.
FIG. 2 shows a conventional switch mechanism. A switch 10 is mounted in a holding member 11, and the holding member 11 has a rotation shaft 20 and is mounted in a body of an image forming apparatus such as a printer shown in FIG. 1. In the holding member 11 of the switch 10, the rotation force is applied to the switch 10 by a spring 13 (elastic member) in a direction away from a pressing member 14. If the pressing member 14 and another pressing member 15 that is provided on the opposite side (upper side in an example of the drawing) of the holding member 11 are inserted, the switch 10 is first turned on.
In this interlock switch, if the distance of a front end of the pressing member 14 and the switch 10 changes due to dimensional errors or attachment errors of components, an arm 10a of the switch 10 may be inserted into a body (case or body) of the switch 10 beyond necessity and may plastically deform. As a result, erroneous detection may be generated and the switch 10 may be broken.
That is, in an interlock switch that is turned on/off by pressing members disposed in two facing door covers of an apparatus body supporting the interlock switch, the door covers being supported by the apparatus body so as to be opened and closed, in a switch mechanism in which a switch having an arm as an actuator is fastened to a switch holding member, the switch holding member is rotatably disposed in the apparatus body, and an ON position of the switch is regulated by an elastic member in a releasing direction in arm-side view, and which is pressed by one pressing member from the arm side and pressed by another pressing member from the side opposite to the arm side and can be turned on, if the pressing amount of a pressing means changes due to dimensional errors of the pressing member or attachment errors of doors, an operation failure or breakage of the switch may be caused.
For example, Japanese Patent Application Laid-open No. H10-162684 discloses an apparatus that has door covers opened and closed in plural direction and needs to operate an interlock apparatus with respect to each of the door covers, and can satisfy functions by the interlock apparatus of one system, even when the door covers are simultaneously opened, regardless of an opening/closing sequence of the door covers. This apparatus suggests an interlock mechanism of sides that go straight to each other.
Japanese Patent Application Laid-open No. 2006-164918 discloses an apparatus that can turn a switch ON and OFF and prevent the switch from being broken, even when the pressing amount of a pressing means changes due to a dimensional error of the pressing means or an attachment error of a door. A switch unit that includes an elastic member to apply a force to the switch in a pressing direction is suggested. In this switch unit, the switch and the pressing member are in a one-to-one relation.